RALEIGH, North Carolina,  (Reuters) – Former Olympic  and world champion Justin Gatlin warned kingpins Usain Bolt and  Tyson Gay to brace for a possible defeat when the American  sprinter returns from a four-year doping suspension this year.

“I could beat them before. I don’t see why I can’t run with  them now,” Gatlin told Reuters in a telephone interview after a  training session in Naples, Florida. “Times don’t scare me.”

Jamaica’s Bolt holds the 100 metres world record at 9.58  seconds and the 200 metres record with a time of 19.19, while  American Gay is the 100 metres world silver medallist.

Gatlin tested positive in 2006 for banned male sex hormone  testosterone but has denied ever knowingly taking any banned  substances. He will be eligible to run again on July 25 under  the terms of his suspension.

“You’ve got to respect the times, they are fast times,” said  Gatlin, who turns 28 in February. “But I feel that if one man  can do it, then the next man can do it as well.”

Gatlin has personal bests of 9.85 in the 100 and 19.86 in  the 200. In 2006 he ran a world-record equalling 9.77 in the 100  but it was wiped out as part of his doping suspension.

He is also the 2004 Olympic 100 metres champion and 200  metres bronze medallist and swept both sprints at the 2005 world  championships.

Whether he will ever face Bolt and Gay again is up in the  air since major European organisers agreed in principle not to  invite athletes like Gatlin and Britain’s Dwain Chambers who  have served lengthy doping bans.